Process for the preparation of fatty amides



PRQCESS FOR THE PREPARATION OF FATTY Al IDES Louis Gene Rieciardi,Brooklyn, N. Y., and Joseph Philip Di Geronimo, Jersey City, N. J.,assignors to Colgate- Palmolive Company, Jersey City, N. J., acorporation of Delaware No Drawing. Application February 28, 1955 SerialNo. 491,176

8 Claims. (Cl. 260-404) The present invention relates to the productionof fatty amides and has particular reference to an improved process forthe manufacture of fatty amides from fatty triglycerides and anamidating agent.

Heretofore, it has been proposed to prepare fatty amides by reactingfatty triglycerides with hydroxy alkyl amine in the presence of analkali metal alkoxide catalyst, preferably in the absence of aqueousmedium. The fatty material and the amine form two separate phases, andin order to obtain a desirably rapid operation of such a process it hasbeen necessary to subject the reactants to elevated temperatures, e. g.100 C. For example, the prior art teaches the amidation of fats such asrape oil and hydrogenated castor oil with monoethanolamine containingsodium in solution by heating these reactants, with stirring, at 100 C.until the mixture becomes homogeneous. Once the mixture has becomehomogeneous an exothermic reaction occurs, going almost to completionwithin a few minutes to produce a solution of glycerine in themonoethanolamides of the fatty acids present. It has now been found thatthe achievement of such a homo geneous mass, as contrasted to the twosubstantially immiscible liquid phases previously present, is one of thecontrolling factors dictating the use of elevated temperatures in thepreviously proposed process, since operation at such elevatedtemperatures greatly diminishes the period of time required to obtainhomogeneity, assuming other factors such as agitation and catalystcontent to be constant.

The novel process of the present invention facilitates the rapidformation of a homogeneous mixture at a relatively low temperature thusenabling the use of lower temperatures for the ensuing exothermicamidation reaction. Operation of such an exothermic reaction at lowtemperatures is thermodynamically desirable in that it increases theequilibrium yield of the desired product and also results in theproduction of products of improved color and purity by virtue ofreducing the extent of undesirable side reactions and thermaldegradation of the reactants and products.

In accordance with the present invention fatty triglyceride and lowermonohydric alcohol are commingled in the presence of alkali metalalkoxide and the resulting mixture of said triglyceride, alcohol andalkoxide is reacted with hydroxy alkyl amine. While the reaction may becarried out at higher temperatures, it is desirable to realize theadvantages inherent in operating at relarively low temperatures such asfrom room temperature to about 80 C., and preferably at about 55 C. to60 C. The reaction mixture rapidly become homogeneous and thereupon anexothermic amidation reaction ensues.

it will be understood that the alkali metal alkoxide may be added to thefatty triglyceride as such or in a manner such as to generate alkalimetal alkoxide in situ. It is a preferred embodiment of the presentinvention to add the alkali metal alkoxide and lower monohydric alcoholas a unity to the fatty triglyceride, said unity having previously beenprepared by reacting alkali metal with an ite States Patent Q1 iceexcess of lower monohydric alcohol. Gbviously however, these materialsmay be added to the fatty triglyceride as separate entities, the orderof addition being immaterial.

Although the fatty triglyceride may be in solid form at the time of thepretreatment with catalyst and alcohol, it is preferred to employtriglyceride which is in the liquid state. Naturally it is alsodesirable to perform this step at as low an operating temperature aspossible so as to minimize deterioration and darkening of the reactants.

In carrying out the process of the present invention, the molar ratio offatty triglyceride to lower monohydric alcohol must be within the rangeof 1:0.25 to 1:2, preferably about 1:1. If the ratio of triglyceride toalcohol is outside of these limits, the advantages of the presentprocess are not fully realized. Normally the molar ratio of fattytriglyceride to alkali metal alkoxide is about 1:0.045 to 1:03,preferably about 1:02. The mixture of triglyceride, alcohol and alkoxideis reacted with the hereinafter defined hydroxy alkyl amine inproportions equal to or in slight molar excess of the fatty acids of thetriglyceride, i. e. the molar ratio of fatty acids in said triglycerideto hydroxy alkyl amine is within the range of about 1:1 to 1:1.3.

It has been found that when fatty triglyceride is contacted, in thepresence of a small amount of alkali metal alkoxide, with about 0.25 to2 moles of lower monohydric alcohol per mole of said triglyceride, arapid reaction occurs even at room temperature to produce a considerablequantity of fatty monoglycerides. The mixture normally also takes on aloose gel-like structure, possibly resulting from the formation of soapsby reaction between alkali metal and the fatty acid radicals released bythe formation of the monoglyceride. The mechanisms of the gel formationand chemical reaction are not fully understood, however it is believedthat the monoglyceride-containing loose gels are peculiarly subject torapid diffusion by and chemical reaction with hydroxy alkyl amine, thusfacilitating the rapid attainment of a homogeneous reaction mass atrelatively low temperatures.

Fatty triglycerides suitable for amidation in accordance with thepresent invention are those containing fatty acid radicals predominantlyof about 10 to 20 carbon atoms and preferably about 12 to 16 carbonatoms. Examples of preferred glycerides are those derived from lauric,myristic and palmitic acids, natural products such as coconut, palmkernel, and babassu oils being eminently suited for the present process.Other suitable triglycerides include lard, corn oil, cottonseed oil,tallow and soy bean oil.

The term hydroxy alkyl amine as used in the present specification and inthe appended claims refers only to those hydroxy alkyl amines wherein analkyl group joins at least one esterifiable hydroxy group to at leastone nitrogen atom to which there is attached at least one replaceablehydrogen atom. Among the representative hydroxy alkyl amines which maybe used are, for example, monoethanolamine, diethanolamine,monopropanolamine, dipropanolamine, isopropanolamine, dibutanol amine,monobutanolamine, mouoisobutanolamine, monoand dipentanolamine, monoanddihexanolamine, mono and dioctanolamine, monolaurylolamine,monohexadecylolamine, monoethyl ethanolamine, mono-octadecylolamine,monobutyl ethanolamine, cyclohexyl ethanolamine, ethanolaniline,Z-methylamine-propane-diol-1,3, 1 phenol amine propane diol 2,3, lhydroxyethylamino 2 methoxypropan-ow, diglyceron monoamine, diglyceroldiamine, and the like. It is a preferred embodiment of the invention,however, to use those hydroxy-alkyl amines having up to 4 carbon atomsin each alkyl radical, such as monoethanolamine, diethanolamine andmonoisopropanolamine.

The lower monohydric alcohols to be used in the aseaeta 3 process of thepresent invention are those aliphatic alcohols containing up to about 5carbon atoms, examples thereof being methanol, ethanol, isopropanol, andbutanol, methanol being preferred.

The 'alkali metal alkoxide catalyst referred to is well known to the artand is not a novel feature of the present invention. The catalyst isderived from lower monohydric alcohols having up to about 5 carbonatoms, such as methanol, ethanol, isopropanol and butanol, methanolbeing preferred. The catalyst may desirably be prepared by treatingexcess lower monohydric alcohol with alkali metal so as to produce asolution of alkali metal alkoxide in a lower monohydric alcohol suitablefor direct addition to the fatty triglyceride as described previously.The catalyst may also be prepared in other manners using any materialcapable of reacting with lower monohydric alcohols to form alkali metalalkoxide. Suitable alkali metals include sodium, potassium and lithium.

It is understood, of course, that the term catalyst is used herein inreference to alkali metal alkoxides in the sense previously used in theamidation art. That is, it refers to a material which is employed inminor amounts to increase the rate of production of a desired product,and is not necessarily present in its original form at the end of thereaction.

In order to indicate even more fully the nature of the present inventionthe following examples are set forth. It will be understood that theseexamples are presented for illustrative purposes only and that it is notintended to limit the scope of the invention in any manner. It will berealized by those skilled in the art that the invention is notrestricted to the examples except as indicated in the appended claims.

Example I Approximately 0.2 gram moles of coconut oil at about 30 C. areplaced in a 300 milliliter three necked spherical glass flask, the lowerone-third of which is covered by an electrical heating mantle. Anelectrically driven glass stirrer continuously agitate's the contents ofthe flask at about 500 R. P. M. A solution of 0.037 gram moles of sodiummethoxide in about 0.18 gram moles of methanol is added to the flask andis allowed to interact with the coconut oil for approximately twominutes at about 36 C. During this period the contents of the vesselform a loose gel, and analysis of a sample of the contents of the flaskindicates a monoglyceride content of approximately At the end of the twominute pretreatment period, 0.67 gram moles of diethanolamine are addedto the flask and form a separate liquid phase therein. The cont nts ofthe flask are then heated to about 60 C. by means of the previouslydescribed electric heating mantle. Within two minutes of reaching about60 C., the contents of the flask become homogeneous and a typicalexothermic amidation reaction occurs largely within about 2 minutes.

In contrast to the above example, if the same mixture of catalyst andlower monohydric alcohol is added to the diethanolamine, two andone-half times as much catalyst is required to achieve homogeneitywithin the same period of time under the same conditions of temperatureand agitation, or as an alternative, the final mixture of reactants mustbe heated to a temperature of about 77 C.

Example II Approximately 0.2 gram moles of coconut oil at about 30 C.are placed in a 300 milliliter three necked spherical glass flask, thelower onethird of which is covered by an electrical heating mantle. Anelectrically driven glass stirrer continuously agitates the contents ofthe flask at about 500 R. P. M. A solution of 0.018 gram moles of sodiummethoxide in about 0.09 gram moles of methanol is added to the flask andis allowed to interact.

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with the coconut oil for approximately two minutes at about 30 C. Duringthis period the contents of the vessel form a loose gel.

At the end of the two minute pretreatment period, 0.67 gram moles ofdiethanolamine are added to the flask and form a separate liquid phasetherein. The contents of the flask are then heated to about 78 C. bymeans of the previously described electric heating mantle. Within twominutes of reaching about 78 C., the contents of the flask becomehomogeneous and a typical exothermic amidation reaction occurs largelywithin about 2 minutes.

In contrast to this example, if the same mixture of catalyst and lowermonohydric alcohol is added to the diethanolamine, approximately twotimes as much catalyst is required to achieve homogeneity within thesame period of time under the same conditions of temperature andagitation, or as an alternative, the final mixture of reactants must beheated to a temperature of about 90 C.

Although the present invention has been described with reference toparticular embodiments and examples, it will be apparent to thoseskilled in the art that variations and modifications of this inventioncan be made and that equivalents can be substituted therefor withoutdeparting from the principles and true spirit of the invention.

What is claimed is:

1. A process for the preparation of fatty acid hydroxy alkyl amideswhich comprises reacting fatty triglyceride with lower monohydricalcohol in the presence of alkali metal alkoxide having up to about 5carbon atoms to form a reaction product containing fatty acidmonoglycericle, the molar ratio of said fatty triglyceride to saidmonohydric alcohol being within the range of 1:025 to 1:2, and reactingthe thus formed fatty acid monoglyceride-containing reaction productwith hydroxy alkyl amine selected from the group consisting of hydroxylower alkyl mono and di amines having up to 4 carbon atoms in each alkylradical therein to form fatty acid hydroxy alkyl amide.

2. A process for the preparation of fatty acid hydroxy alkyl amides asset forth in claim 1 wherein said fatty acid monoglyceride-containingreaction product is reacted with said hydroxy alkyl amine at atemperature from room temperature to about 80 C.

3. A process for the preparation of fatty acid hydroxy alkyl amides asset forth in claim 1 wherein said fatty acid monoglyceride-containingreaction product is reacted with said hydroxy alkyl amine at atemperature of about to C.

4. A process for the preparation of fatty hydroxy amides which comprisesreacting fatty triglyceride containing fatty acid radicals predominantlyof about 10 to 20 carbon atoms with lower monohydric aliphatic alcoholcontaining up to about 5 carbon atoms in the presence of alkali metalalkoxide containing up to about 5 carbon atoms to form a reactionproduct containing fatty acid monoglyceride, the molar ratio of saidtriglyceride to alcohol being within the range of about 1:0.25 to 1:2,and reacting the resulting mixture of said monoglyceride, triglyceride,and alkoxide with hydroxy alkyl amine selected from the group consistingof hydroxy lower alkyl mono and di amines having up to 4 carbon atoms ineach alkyl radical therein, said reaction with said hydroxy alkyl aminebeing carried out at a temperature from room tem- 5 to 1:2 and the molarratio of said triglyceride to alkoxide being within the range of about120.045 to 1:0.3, and reacting the resulting mixture of saidmonoglyceride, triglyceride, alcohol and alkoxide with hydroxy alkylamine in slight molar excess of said fatty acid of said mixed fattymonoglyceride and triglyceride, said hydroxy alkyl amine selected fromthe group consisting of hydroxy lower alkyl mono and di amines having upto 4 carbon atoms in each alkyl radical therein and said reaction withsaid hydroxy alkyl amine being carried out at a tempera- 4 ture fromroom temperature to about 80 C.

6. A process for the preparation of fatty hydroxy amides as set forth inclaim 5 wherein the molar ratio of said fatty triglyceride to lowermonohydric alcohol is about 1:1.

7. A process for the preparation of fatty hydroxy amides as set forth inclaim 5 wherein the ratio of said 6 fatty triglyceride to hydroxy alkylamine is within the range of about 1:1 to 121.3.

8. A process for the preparation of fatty hydroxy amides which comprisesreacting coconut oil with methanol in the presence of sodium methoxideto form a reaction product containing coconut oil fatty acidmonoglyceride, the molar ratio of said coconut oil to said methanolbeing Within the range of 1:0.25 to 1:2, and

reacting the resulting mixture of said monoglyceride, I

coconut oil, methanol and sodium methoxide with diethanolamine at atemperature from room temperature to about 80 C.

References Cited in the file of this patent UNITED STATES PATENTS2,464,094 Meade Mar. 8, 1949

1. A PROCESS FOR THE PREPARATION OF FATTY ACID HYDROXY ALKYL AMIDESWHICH COMPRISES REACTING FATTY TRIGLYCERIDE WITH LOWER MONOHYDRICALCOHOL IN THE PRESENCE OF ALKALI METAL ALKOXIDE HAVING UP TO ABOUT 5CARBON ATOMS TO FORM A REACTION PRODUCT CONTAINING FATTY ACIDMONOGLYCERIDE, THE MOLAR RATIO OF SAID FATTY TRIGLYCERIDE TO SAIDMONOHYDRIC ALCOHOL BEING WITHIN THE RANGE OF 1:0.2K TO 1:2, AND REACTINGTHE THUS FORMED FATTY ACID MONOGLYCERIDE-CONTAINING REACTION PRODUCTWITH HYDROXY ALKYL AMINE SELECTED FROM THE GROUP CONSISTING OF HYDROXYLOWER ALKYL MONO AND DI AMINES HAVING UP TO 4 CARBON ATOMS IN EACH ALKYLRADICAL THEREIN TO FORM FATTY ACID HYDROXY ALKYL AMIDE.